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MG MGB Technical - auto tranny kick down trouble (non MGB)

Sorry to take up space with a non-mgb topic, but you folks have been so great with all my MG problems I had to give you a go with this Plymouth problem.
I have a '64 Valiant Barracuda with the 273 V8 and Carter 2 bbl, and a TorqueFlite push button auto tranny. It stalled a lot when cold and after inspecting the carb I discovered it was pretty well gummed up. So I bought a
rebuild and recently intstalled it. Now it starts fine and has no idling problems, and the choke even works. However it still stalls when the engine is cold when the tranny is trying to kick down. Some times it is only a
momentary gasp and keeps running, but sometimes it dies altoghether. Any ideas what would cause this to happen? Can anyone help on this problem?
Bill
Bill Mertz

That's a fairly odd failure mode... normally I'd only expect an engine to try and stall when the trans is shifting UP or when putting it in gear. When it's kicking down it suggests you've got your foot on the gas anyway so the engine should be making plenty of power.

Does the TF have a kickdown cable and vacuum modulator? If the cable was set up wrong perhaps the transmission would be trying to kick down at the wrong time, which might upset the engine. If there was a *bad* modulator leak, it might be managing to lean the engine out sometimes, but you'd notice that the rest of the time.

I'm sure there's people here who know about the TF (I only know about TH350) so hopefully someone will chip in, but if you don't I recommend visiting the forum on www.hotrodders.com where there's lots of people using all sorts of american engines and transmissions.

hth,
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Olly
Oliver Stephenson

Really clutching at straws here, but...when the gearbox kicks down, it's trying to increase the engine speed pretty quickly. Although there's then going to be less load on the engine, it's being forced to run faster...so I guess it could still be an induction or ignition problem?

Tim
Tim Jenner

Could be two things - choke coming off too fast, or not set rich enough; or not enough accelerator pump shot. As memory serves, these engines had a bi-metal spring in the intake manifold with linkage up to the choke control arm. These springs are replaceable and weren't expensive (but that was a long time ago).

Wayne
Wayne Pearson

I've owned some older MOPAR's an your description sounds like your choke is out of adjustment. Had a Dart used to do the same thing. Ended up installing a manual choke.
R. L Carleen

MOPARS usually use a rod linked to the throttle shaft for the kick down, no modulator is used. As Wayne said it sounds like you may have a problem in the accelerator pump circuit or in the choke. I don't think the kick down is the problem. FWIW, Clifton
Clifton Gordon

Ah, it's bogging while you're actually moving the pedal down, that makes more sense.

I think even with healthy throttle pumps it'll still die when it's cold. You need chokes as well if you want decent response right from startup, so that's probably where to look. However this is only as I have found it to be with a 4-barrel holley, so ymmv.

ttfn,
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Olly
Oliver Stephenson

I had an auto that used to stumble when flooring the throttle, that was due to the tight-wads at Ford failing to fit a ground wire in the dizzy betwen the fixed and moving points plates, just relying on a sliding contact. Large throttle opening caused large vacuum changes which caused large movements of the plate and the sliding contacts weren't up to it.
Paul Hunt

Sounds like the choke adjustment should be my first point of attack. Since the carb is new (rebuilt), and it had this problem with both old and new carb, I was a bit skeptical that it was the carb at all. But I'll recheck the choke adjustment (if I can figure out the proper way to set it).
Bill
Bill Mertz

This thread was discussed between 24/04/2003 and 25/04/2003

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